673

 To add values to previous values in a list, use the
 following formulation:
 ----------------------------------------------------
 a_list = [0, 0, 0]
 integers_to_add = [1, 2, 3]

 for index, integer in enumerate(integers_to_add):
    a_list[index] += integer

 print(a_list)
 OUTPUT
 [1, 2, 3]
 -----------------------------------------------------
 https://tinyurl.com/yekxf6fc